This invention relates to an improved locking means for horizontally sliding doors of the type commonly used for allowing access to patios and the like. In particular, the invention relates to four-panel sliding doors which include two fixed end panels and two center sliding panels. Such four-panel sliding doors heretofore have not been deemed very efficient from a security and strength standpoint and in terms of their ability to exclude the elements. This deficiency is due mainly to the unavailability of any adequate and sufficiently economical locking means to join together the meeting vertical stiles of the two sliding center door panels. The principal objective of this invention, therefore, is to completely satisfy this need for a better joining and locking means for the two center sliding panels of four-panel doors, thereby enabling such doors to possess adequate stability in all directions and to have adequate resistance to penetration by the elements when closed and locked.
Briefly stated, the objective of the invention is achieved by the provision within the opposing vertical tongue and groove interfitting stiles of the center sliding panels of the door of two separate cooperating locking devices which effectively secure the sliding panels in closed and locked positions with strength and stability against external forces exerted in any direction. The two separate locking devices are placed at a location where tongue and grooved portions of the meeting vertical stiles interfit, thus offering a maximum resistance to horizontal displacement of the sliding panels while avoiding any tendency for the sliding panels to torque and bind in their trackways, as may tend to occur when locking means are eccentrically located or remote from the plane of interengagement of the tongue and groove portions of the sliding panels.
According to the invention, one of the aforementioned locking devices consists of a vertical axis sliding bolts within the vertical stile of the usually inactive sliding panel immediately adjacent to the groove of the stile which receives the tongue of the stile on the active sliding door panel. The other locking device consists of a lever operated swinging latch bolt built into the vertical stile of the active sliding door panel also closely adjacent to the interfitting tongue and groove portions of the two sliding panels. The latter swinging latch bolt is employed in conjunction with an adjacent rigid anti-lift tab in the active sliding panel which enters a slot provided in the stile of the opposing inactive sliding panel. The arrangement is extremely efficient in achieving the stated objective of the invention, and in greatly improving the operational efficiency, convenience and overall security of four-panel sliding doors, thereby rendering the same much more practical and more carefree in use.
Other features and advantages of the invention will become apparent to those skilled in the art during the course of the following detailed description.